When Ford wants to try out a new transmission part, an engineer sends a digital blueprint of the component to a computer, and what happens next once seemed like the stuff of science fiction.

Inside a device about the size of a microwave oven, a plastic, three-dimensional version of the component begins to take shape before your eyes. After scanning the design blueprint, the gadget fuses together a paper-thin layer of plastic powder. It repeats, putting another layer on top, and then thousands more, before binding the material together with lasers. A few hours later, out pops the auto part, ready to be tested.

The cost of such technology: about $1,500.

At such prices, 3-D printers, once an obscure and expensive innovation, are gaining traction among businesses, with broad implications for manufacturing. Ford is putting them in the hands of every one of its engineers. NASA uses the printers to test parts that could eventually make it to space.

And pretty soon, analysts say, they will be showing up in the home office. Just a few years ago, 3-D printers were as big as industrial refrigerators and cost hundreds of thousands of dollars each. Now anyone can order one online and put it on a desk.

That such technology can be offered so cheaply and compactly may be these gadgets' true breakthrough.

"You can argue this is the democratization of manufacturing," said Carl Howe, head of consumer research at Yankee Group, a tech research firm. He predicted that this will be the year when 3-D printers will become inexpensive enough to gain wider interest from small businesses, colleges and consumers.

"Things that used to require tens or hundreds of thousands of dollars for plastic molds, you can now do for $1,500 or less," Howe said.

This is definitely the year that 3-D printing is making a splash at the International Consumer Electronics Show, the annual bazaar of geek commerce. Last year, only one 3-D printing company showed up at the CES, which aims to showcase gadgets you might buy at Best Buy or Amazon, not at industrial supply stores. This week, four such companies will be there.

One of them — MakerBot, which also supplies devices to Ford — will unveil Tuesday a new 3-D printer designed to be the most advanced ever offered at a price that could make it attractive to the home hobbyist.

The online world of hackers and tech enthusiasts is buzzing about how to use such a powerful tool. Researchers and early adopters have made everything from cute figurines and jewelry to working bicycles. A lot of iPhone cases are being custom-made on 3-D printers.

Some other possibilities have been more controversial.

After the massacre at Sandy Hook Elementary School, a video proposing the use of a 3-D printer to make a copy of a gun that fires real bullets went viral on the Web. University of Texas law student Cody Wilson explained in the video that what he called the Wiki Weapon would create the "first 3-D printable personal defense system."

"What's great about the Wiki Weapon is it only needs to be lethal once," Wilson, who heads a nonprofit called Defense Distributed, says in the video. "We will have the reality of a weapons system that can be printed out from your desk. Anywhere there is a computer, there is a weapon."

Rep. Steve Israel, D-N.Y., said the creation of guns through 3-D printing could make undetectable plastic firearms too easy to acquire. At a news briefing in December, he called for the renewal of the Undetectable Firearms Act, which would include bans on plastic guns and firearms made from 3-D-printed parts.

"It is just a matter of time before these three-dimensional printers will be able to replicate an entire gun," Israel said. "And that firearm will be able to be brought through this security line, through the metal detector, and because there will be no metal to be detected, firearms will be brought on planes without anyone's knowledge."

Eventually, 3-D printers are expected to make even more complex parts and machines, or be used in medicine for hip replacements and spinal reconstruction. That stands to revolutionize far more than home hobbies.

"Before, if you were a manufacturer and you wanted to make a product, you had to make 10,000 or 100,000 of them; you had to think in terms of the capital it costs to make that volume," said Bre Pettis, chief executive of MakerBot. "It takes hours. Now you can iterate on an idea many times in one day and create huge efficiencies."

And while once such automation primarily threatened to replace workers in repetitive assembly-line jobs, now these technologies are taking aim at higher-level jobs that had seemed suitable only for humans.

"A more productive society is good news, and it allows us to have greater variety and choices," said Andrew McAfee, principal research scientist at MIT's Center for Digital Business. "What concerns me are the labor-force consequences of such astonishing changes."